In general, Russian resident is subject to Russian income tax on their worldwide income, including income earned abroad.
Annual incomes of more than RUB 5 million (~$70,775) are subject to a 15% tax rate. It might be somewhat different since it also depends on individual circumstances.
Let's see, how much Andrey Rublev, resident of Moscow and current #5 tennis player in the world has earned by playing tennis under a neutral flag since the full-scale Russian invasion of Ukraine started in February 2022:
- ATP Masters 1000 Indian Wells, semi-finals - earned $343,985
- ATP Masters 1000 Miami, the round of 64 - earned $30,130
- ATP Masters 1000 Monte Carlo, the round of 16 - earned $79,230 (€72,865)
- Belgrade, winner - earned $87,930 (€81,310)
- ATP Masters 1000 Madrid, quarter-finals - earned $210,366 (€169,650)
- ATP Masters 1000 Rome, the round of 32 - earned $41,216 (€39,070)
- Roland Garros Paris, France, quarter-finals - earned $395,607 (€380,000)
- Halle, the round of 32 - earned $17,877 (€16,650)
- Bastad, semi-finals - earned $28,374 (€27,885)
- Hamburg, the round of 16 - earned $26,106 (€25,900)
- Washington, semi-finals - earned $94,840
- ATP Masters 1000 Canada, the round of 32 - earned $42,760
- ATP Masters 1000 Cincinnati, the round of 16 - earned $84,510
- US Open, quarter-finals - earned $445,000
- Astana, semi-finals - earned $101,890
- Gijon, winner - earned $93,090 (€95,015)
- Vienna, the round of 16 - earned $33,638 (€34,355)
- ATP Masters 1000 Paris, the round of 16 - earned $72,680 (€72,865)
- Nitto ATP Finals, semi-finals - earned $1,086,600
- Adelaide 1, the round of 32 - earned $6,340
- Adelaide 2, the round of 16 - earned $11,280
- Australian Open, quarter-finals - earned $384,400 (A$555,250)
For comparison, it costs ~$300,000 to produce a Tochka-U missile used in Ukraine by Russian troops.
You can stop tennis players from showing their flag during a game, but you can't stop them from paying taxes in their own country that is waging a bloody war of conquest.
Because of that, Russian athletes must be banned from playing professional sports until their country of residence stops the bloodshed!